Consumer requirements have required larger and larger sensor arrays. However, as a sensor array gets larger, it becomes more difficult to reliably fabricate the sensor array. Fabrication yield and sensor cost can be proportional to the size of the sensor array.
Typically, any bad portion in a sensor array requires that the sensor array be discarded or used for another purpose. However, there have been attempts to incorporate circuitry which compensates for fabrication errors.
Such errors can be corrected using a median of a neighborhood surrounding the faulty pixel.
The median also has other applications which are well known in the art.